CARTILAGE AND BONE METABOLISM IN RHEUMATOID-ARTHRITIS - DIFFERENCES BETWEEN RAPID AND SLOW PROGRESSION OF DISEASE IDENTIFIED BY SERUM MARKERS OF CARTILAGE METABOLISM

Serum concentrations of specific cartilage and bone molecules reflecti ng tissue turnover were measured in two well-defined patient groups wi th early rheumatoid arthritis with distinctly different disease outcom e to see if early differences in their levels are prognostic of the ra te of joint destruction. Compared with a matched normal population, in creased concentrations of cartilage oligomeric matrix protein (COMP) w ere found in all patients who developed rapid hip joint destruction. I n contrast, levels of a putative marker of cartilage aggrecan synthesi s, the chondroitin sulfate epitope 846, were increased only in patient s with slow joint destruction. Levels of bone sialoprotein (BSP) were increased in both groups, as were levels of the C-propeptide of type I I procollagen (CPII), a marker of collagen II synthesis. The increased concentrations of the 846 epitope in patients with slow joint destruc tion suggest increased aggrecan synthesis. The low levels of the 846 e pitope in patients with rapid joint destruction, concomitant with elev ated levels of CPII, suggest a selective increase in collagen synthesi s. The elevated BSP levels indicate an increased bone turnover in both groups. Thus elevated serum levels of COMP may indicate an unfavorabl e prognosis for rapid joint destruction, whereas elevated 846 epitope indicates a more favorable prognosis.